Figure 2.

Effects of hTERT-siRNA combined with doxorubicin on the proliferation of breast cancer cells. The MCF-7 (A) and MDA-MB-453 (B) breast cancer cells were either untreated or treated with 0.5 μM doxorubicin 12 h after the siRNA transfection. Cell viability was measured by the MTT assay every day for 4 days. Data are shown as mean ± SD from three independent experiments. Panel C and D show the inhibition effect of hTERT siRNA on the tumorigenic potential of human breast cancer cells. 2 × 10⁶ MCF-7 cells (C) or MDA-MB-453 cells (D) that were untreated or transfected with control siRNA or hTERT siRNA were injected subcutaneously into each flank of athymic nude mice. The tumor dimensions were measured every 3 days. The mean tumor volume (mm³) was calculated according to the formula: (d² × D)/2, where d and D are the shortest and longest diameters of the tumor, respectively. All measurements were performed in a coded, blinded fashion. Data are shown as mean ± SD with 5 mice per treatment group.